Strained silicon engineering has become a key innovation to enhance device on-current. It has allowed the IC industry to keep on the scaling path and assure a performance gain from one technology node to the next. Uniaxial strained silicon has already made its way into 90nm IC manufacturing. Biaxial wafer level strain may be the next step for boosting transistor performance. At the substrate level, strained silicon on insulator is a major innovation that offers higher carrier mobility, combining the advantages of SOI with those of strained silicon. This review focuses on the development of strained silicon, its impact on device properties and its scalability beyond 65nm design rules.